In a report ahead of the G20 summit in Brisbane, Oxfam said the wealth of G20 nations had risen by US$17 trillion since December but the richest one percent of people took more than one-third of this with USD 6.2 trillion.
"The widening gap between rich and poor is increasing... so inequality is becoming more pronounced," Oxfam Australia chief Helen Szoke told AFP.
"Inequality in and of itself is problematic for those people who are left behind but we also know that you can't actually achieve growth unless you address this issue of inequality."
Led by Australia, G20 nations have pledged to raise the level of their combined output by at least two percent above the currently projected level in the next five years, in hopes of creating millions of jobs and prodding stalling economies.
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But Szoke said while the grouping was committed to growing GDP, any focus on inclusive growth, which brings benefits to the community more broadly, had been lost.
But Szoke said the issue of the Ebola outbreak in west Africa also needed to be addressed, warning that it could have knock-on economic impacts.
"The G20 cannot ignore Ebola because Ebola is the symbol of what happens when there is stark social and economic inequality where you don't have the social protections and public infrastructure to deal with what is a containable disease," she said.
"When Ebola has occurred in other countries like Uganda it has been able to be contained."